This study aims to measure the space charge of extremely thick insulating systems,such as full-scale ultrahigh-voltage cables and joint boxes,with high accuracy using the pulse electroacoustic method.The proposed meth...This study aims to measure the space charge of extremely thick insulating systems,such as full-scale ultrahigh-voltage cables and joint boxes,with high accuracy using the pulse electroacoustic method.The proposed method employs an electrically insulating acoustic coupler to improve acoustic matching.Additionally,a metallic backing with high acoustic impedance is applied to upgrade the sensitivity to almost five times that of conventional measuring systems.However,the proposed structure requires an extremely thick backing material to avoid multiple reflections when the specimen thickens.In this study,a backing structure that combines a thin polymer plate with an air layer is proposed.Because multiple reflections are not returned from the air layer,the backing structure can be designed to be extremely small,thereby maintaining high sensitivity.This advantage is verified experimentally.展开更多
The space-charge distributions of electric double-layer capacitors （EDLCs）, which are energy storage devices, were examined with the pulsed electroacoustic （PEA） method. It was found that the experimental results ...The space-charge distributions of electric double-layer capacitors （EDLCs）, which are energy storage devices, were examined with the pulsed electroacoustic （PEA） method. It was found that the experimental results could be influenced by the reflection and penetration of sound waves when the space-charge dis- tributions of EDLCs were measured with the PEA method. This is because EDLCs have a five-layer structure consisting of three materials （aluminum, cellulose, and activated carbon）. We calculated the reflection wave components that influenced the charge density through the acoustic impedance and the relative permittivity of the materials. In this way, we found that the changes in the space-charge distributions of EDLCs and their charge characteristics corresponded closely. We determined that measuring the space- charge distributions with the PEA method was effective for evaluating the charge accumulation of EDLCs. In this study, a polarized electrode was prepared for use in EDLCs. The ratio of the surface area to the average pore diameter of the polarized electrode was measured with the nitrogen adsorption method at 77 K. The relationship between the ratio of the surface area to the average pore size and the space-charge distributions of EDLCs is also discussed in this paper.展开更多
Increased renewable energy integration and international power trades have led to the construction and development of new HVDC transmission systems.HVDC cables,in particular,play an important role in undersea power tr...Increased renewable energy integration and international power trades have led to the construction and development of new HVDC transmission systems.HVDC cables,in particular,play an important role in undersea power transmission and offshore renewable energy integration having lower losses and higher reliability.In this paper,the current commercial feasibility of HVDC cables and the development of different types of HVDC cables and accessories are reviewed.The non-uniform electric field distribution caused by the applied voltage,temperature dependent conductivity,and space charge accumulation is briefly discussed.Current research in HVDC cable for higher operation voltage level and larger power capacity is also reviewed with specific focus on the methodologies of space charge suppression for XLPE extruded cables.展开更多
文摘This study aims to measure the space charge of extremely thick insulating systems,such as full-scale ultrahigh-voltage cables and joint boxes,with high accuracy using the pulse electroacoustic method.The proposed method employs an electrically insulating acoustic coupler to improve acoustic matching.Additionally,a metallic backing with high acoustic impedance is applied to upgrade the sensitivity to almost five times that of conventional measuring systems.However,the proposed structure requires an extremely thick backing material to avoid multiple reflections when the specimen thickens.In this study,a backing structure that combines a thin polymer plate with an air layer is proposed.Because multiple reflections are not returned from the air layer,the backing structure can be designed to be extremely small,thereby maintaining high sensitivity.This advantage is verified experimentally.
基金supported by a Scientific Research Grant from the Japan Society for the Promotion of Science and the Special Coordination Fund for Promoting Science and Technology from the Japanese Ministry of Education, Culture, Sports, Science and Technology and a grant for Scientific Research on Priority Areas from the University of Miyazaki
文摘The space-charge distributions of electric double-layer capacitors （EDLCs）, which are energy storage devices, were examined with the pulsed electroacoustic （PEA） method. It was found that the experimental results could be influenced by the reflection and penetration of sound waves when the space-charge dis- tributions of EDLCs were measured with the PEA method. This is because EDLCs have a five-layer structure consisting of three materials （aluminum, cellulose, and activated carbon）. We calculated the reflection wave components that influenced the charge density through the acoustic impedance and the relative permittivity of the materials. In this way, we found that the changes in the space-charge distributions of EDLCs and their charge characteristics corresponded closely. We determined that measuring the space- charge distributions with the PEA method was effective for evaluating the charge accumulation of EDLCs. In this study, a polarized electrode was prepared for use in EDLCs. The ratio of the surface area to the average pore diameter of the polarized electrode was measured with the nitrogen adsorption method at 77 K. The relationship between the ratio of the surface area to the average pore size and the space-charge distributions of EDLCs is also discussed in this paper.
基金supported by the State Grid Corporation of China:Research on Key Technologies of Insulation Material and Accessories for 320 kV HVDC XLPE Cable System(SGRIZLJS(2014)888).
文摘Increased renewable energy integration and international power trades have led to the construction and development of new HVDC transmission systems.HVDC cables,in particular,play an important role in undersea power transmission and offshore renewable energy integration having lower losses and higher reliability.In this paper,the current commercial feasibility of HVDC cables and the development of different types of HVDC cables and accessories are reviewed.The non-uniform electric field distribution caused by the applied voltage,temperature dependent conductivity,and space charge accumulation is briefly discussed.Current research in HVDC cable for higher operation voltage level and larger power capacity is also reviewed with specific focus on the methodologies of space charge suppression for XLPE extruded cables.
